Analytical methods for the quantitation of drugs in biological matrices were needed for the various phases in the development of two potential anticonvulsant agents, ADD 35002 and ADD 03055. Both these compounds are currently undergoing NINCDS-sponsored clinical efficacy trials, and plasma level measurements are integral to these studies. These measurements had to have specificity and sensitivity in order to quantitate these agents not only for efficacy studies, but also for pharmacokinetic and toxicologic investigation. The methodology involved examination of the physical and chemical characteristics of each compound in order to determine the most suitable chromatographic and detection procedures. It was also noted that ADD 35002 had a metabolite which required quantitation. It was found that all compounds could be analyzed on high performance liquid chromatographs with reverse phase C-18 columns. The detection employed variable wavelength UV and fluorescence monitoring. The sensitivity limits were found to be less than 6 ug/ml for ADD 03055 and less than 10 ng/ml for ADD 35002. Linearity was excellent throughout the range needed for analysis. The final methods were found to be suitable for a variety of both animal and human investigation.